package com.github.gin.sns.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

public class SignatureUtil {

    public static boolean checkSignature(String token,String signature,
                                         String timestamp, String nonce) {
        String[] arr = new String[] { token, timestamp, nonce };  
        Arrays.sort(arr);
        StringBuilder content = new StringBuilder();
        for(String str : arr){
            content.append(str);
        }

        String tmpStr = null;
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-1");
            byte[] digest = md.digest(content.toString().getBytes());
            tmpStr = byteToStr(digest);  
        } catch (NoSuchAlgorithmException e) {  
            e.printStackTrace();  
        }  
        return tmpStr != null && tmpStr.equals(signature.toUpperCase()) ;
    }  
  
    private static String byteToStr(byte[] byteArray) {
        String strDigest = "";  
        for (int i = 0; i < byteArray.length; i++) {  
            strDigest += byteToHexStr(byteArray[i]);  
        }  
        return strDigest;  
    }  
  
    private static String byteToHexStr(byte mByte) {
        char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };  
        char[] tempArr = new char[2];  
        tempArr[0] = Digit[(mByte >>> 4) & 0X0F];  
        tempArr[1] = Digit[mByte & 0X0F];  
  
        return new String(tempArr);
    }  
}
